This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Henrich, C. J. Articles by McMahon, J. B. Search for Related Content PubMed PubMed Citation Articles by Henrich, C. J. Articles by McMahon, J. B.

Research Articles: Therapeutics, Targets, and Development

New inhibitors of ABCG2 identified by high-throughput screening

¹ Basic Research Program, SAIC-Frederick, Inc., ² Molecular Targets Development Program, and ³ Laboratory of Genomic Diversity, NCI Frederick, Frederick, Maryland; ⁴ Medical Oncology Branch, and ⁵ Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland

Requests for reprints: Curtis J. Henrich, Science Applications International Corporation-Frederick, Inc., Building 560, Room 32-63A, NCI-Frederick, Frederick, MD 21702. Phone: 301-846-6054; Fax: 301-846-6177. E-mail: henrichc{at}ncifcrf.gov

Abstract

In order to identify novel inhibitors of the ATP-binding cassette transporter, ABCG2, a high-throughput assay measuring the accumulation of the ABCG2 substrate pheophorbide a in ABCG2-overexpressing NCI-H460 MX20 cells was used to screen libraries of compounds. Out of a library of 7,325 natural products and synthetic compounds from the National Cancer Institute/Developmental Therapeutics Program collection, 18 were found to inhibit ABCG2 at 10 µmol/L. After eliminating flavonoids and compounds of limited availability from the 18 original compounds, 10 of the 11 remaining compounds reversed mitoxantrone resistance in NCI-H460/MX20 cells and prevented ABCG2-mediated BODIPY-prazosin transport in ABCG2-transfected HEK293 cells, confirming an interaction with ABCG2. Based on the activity profiles and the availability of materials, five inhibitors were examined for their ability to compete with [¹²⁵I]iodoarylazidoprazosin labeling of ABCG2, increase binding of the anti-ABCG2 antibody 5D3, and prevent P-glycoprotein or multidrug resistance protein 1–mediated transport. At a concentration of 20 µmol/L, all of the compounds reduced iodoarylazidoprazosin labeling by 50% to 80% compared with controls. All five compounds also increased 5D3 labeling of ABCG2, indicating that these compounds are inhibitors but not substrates of ABCG2. None of the compounds affected P-glycoprotein–mediated rhodamine 123 transport, whereas three affected multidrug resistance protein-1–mediated calcein transport at 25 µmol/L, suggesting that the compounds are relatively specific for ABCG2. These five novel inhibitors of ABCG2 activity may provide a basis for further investigation of ABCG2 function and its relevance in multidrug resistance. [Mol Cancer Ther 2007;6(12):3271–8]

Grant support: Intramural Research Program of the National Cancer Institute, NIH, Center for Cancer Research. This project has been funded in whole or in part with federal funds from the National Cancer Institute, National Institutes of Health, under contract N01-CO-12400. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 5/24/07; revised 9/ 5/07; accepted 10/ 9/07.